At maturity, about 40% of soybean seed dry weight is protein and 20% extractable oil. These constitute the economically valuable products of the soybean crop. Plant oils for example are the most energy-rich biomass available from plants; they have twice the energy content of carbohydrates. It also requires very little energy to extract plant oils and convert them to fuels. Of the remaining 40% of seed weight, about 10% is soluble carbohydrate. The soluble carbohydrate portion contributes little to the economic value of soybean seeds and the main component of the soluble carbohydrate fraction, raffinosaccharides, are deleterious both to processing and to the food value of soybean meal in monogastric animals (Coon et al., (1988) Proceedings Soybean Utilization Alternatives, Univ. of Minnesota, pp. 203-211).
As the pathways of storage compound biosynthesis in seeds are becoming better understood it is clear that it may be possible to modulate the size of the storage compound pools in plant cells by altering the catalytic activity of specific enzymes in the oil, starch and soluble carbohydrate biosynthetic pathways (Taiz L., et al. Plant Physiology; The Benjamin/Cummings Publishing Company: New York, 1991). For example, studies investigating the over-expression of LPAT and DAGAT showed that the final steps acylating the glycerol backbone exert significant control over flux to lipids in seeds. Seed oil content could also be increased in oil-seed rape by overexpression of a yeast glycerol-3-phosphate dehydrogenase, whereas over-expression of the individual genes involved in de novo fatty acid synthesis in the plastid, such as acetyl-CoA carboxylase and fatty acid synthase, did not substantially alter the amount of lipids accumulated (Vigeolas H., et al. Plant Biotechnology J. 5, 431-441 (2007). A low-seed-oil mutant, wrinkled 1, has been identified in Arabidopsis. The mutation apparently causes a deficiency in the seed-specific regulation of carbohydrate metabolism (Focks, Nicole et al., Plant Physiol. (1998), 118(1), 91-101. There is a continued interest in identifying the genes that encode proteins that can modulate the synthesis of storage compounds, such as oil, protein, starch and soluble carbohydrates, in plants.
The biochemical term oxidoreductase refers to enzymes involved in the transfer of electrons from one molecule (the reductant, also called the hydrogen or electron donor) to another (the oxidant, also called the hydrogen or electron acceptor). For some oxidoreductase proteins catalytic properties are known while other proteins are only identified based on the presence of a motif found also in known oxidoreductase enzymes. Small, proteins, 10-30 kDA in size with, with an oxidoreductase motif (ORM) and unknown catalytic properties are prevalent in eukaryotes ranging from unicellular yeast and algae to the animal and plant kingdom. Yoshikawa et al (FEMS Yeast Research (2009), 9(1), 32-44.) disclose that disruption of YPL107W of Saccharomyces cerevisae encoding a protein with oxidoreductase motif and mitochondrial localization is hypersensitive osmotic and ethanol stress. Although proteins with an oxidoreductase motif closely related to that of YPL107W have been identified in every plant that was subjected to in-depth genome or EST sequencing few studies have been conducted on the role of these proteins. In view of the ubiquitous nature of genes encoding ORM proteins in plants further investigation of their role in plant growth and development and specifically in the regulation of storage compound content in seed is of great interest.